title: Brinker possesses multiple mechanisms for repression because its primary co-repressor, Groucho, may be unavailable in some cell types.
abstract: Transcriptional repressors function primarily by recruiting co-repressors, which are accessory proteins that antagonize transcription by modifying chromatin structure. Although a repressor could function by recruiting just a single co-repressor, many can recruit more than one, with Drosophila Brinker (Brk) recruiting the co-repressors CtBP and Groucho (Gro), in addition to possessing a third repression domain, 3R. Previous studies indicated that Gro is sufficient for Brk to repress targets in the wing, questioning why it should need to recruit CtBP, a short-range co-repressor, when Gro is known to be able to function over longer distances. To resolve this we have used genomic engineering to generate a series of brk mutants that are unable to recruit Gro, CtBP and/or have 3R deleted. These reveal that although the recruitment of Gro is necessary and can be sufficient for Brk to make an almost morphologically wild-type fly, it is insufficient during oogenesis, where Brk must utilize CtBP and 3R to pattern the egg shell appropriately. Gro insufficiency during oogenesis can be explained by its downregulation in Brk-expressing cells through phosphorylation downstream of EGFR signaling.
authors.affiliation: Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA.
authors.forename: Priyanka
authors.initials: P
authors.lastname: Upadhyai
authors.forename: Gerard
authors.initials: G
authors.lastname: Campbell
mesh_terms: D000429:Alcohol Oxidoreductases / Q000378:metabolism*; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism*; D056970:Co-Repressor Proteins / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004330:Drosophila / Q000196:embryology* / Q000235:genetics / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D066246:ErbB Receptors / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D055786:Gene Knockout Techniques; D009154:Mutation; D009866:Oogenesis; D010766:Phosphorylation; D018010:Receptors, Invertebrate Peptide / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics; D014921:Wings, Animal / Q000196:embryology*
chemical_list: D000429:Alcohol Oxidoreductases; D051792:Basic Helix-Loop-Helix Proteins; D056970:Co-Repressor Proteins; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D066246:ErbB Receptors; D018010:Receptors, Invertebrate Peptide; D012097:Repressor Proteins; C118082:brk protein, Drosophila; C091023:gro protein, Drosophila; C096794:C-terminal binding protein; C066532:Egfr protein, Drosophila
keywords: Brinker; Co-repressor; CtBP; Groucho; Repression